Every so often you'll find the stars'n'stripes theme in various forms in American magazines: music mags, women's mags, photo mags, fashion mags, and political mags.
Americans love it.
In these mags, there are also abnormal frequency of the word America or American: American Fashion, Sex in America, America's sweetheart; while hardly ever other country or continent's name.
For the average American, America = the world, and that's how Americans like it, and the capitalistic consummeristic America sells by it.
Does other country's magazines frequently cite their own country this or that?
I think it's uniquely US phenomenon.
It is my guess that every American pop magazine has a flag-adorned cover once or more. The ones shown in this page are just the tip of a iceberg. If you spotted one, please let me know!